Heat sink

ABSTRACT

A heat sink includes a base, a first fin provided on the base and including a first cutout portion, a first heat pipe including a first linear portion and a first curved portion, the first curved portion being provided in the first cutout portion, and a second heat pipe including a second linear portion connected to the first fin with an adhesive having a heat conductivity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-299030, filed on Dec. 29, 2009, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a heat sink.

BACKGROUND

A heat source, such as a central processing unit (CPU) or a switching device, of a product diffuses heat, and a heat sink is known, which releases such diffused heat to the outside.

In cases where the product is provided with the heat sink, the heat sink may be often disposed in a limited space. Accordingly, in order to improve efficiency of heat release in the limited space, various approaches have been made.

As one of the approaches, the heat sink may have a heat pipe that is provided to efficiently transfer heat to a fin.

FIG. 7 illustrates a heat sink that is provided with heat pipes. FIG. 8 illustrates a manner in which the heat pipes are provided. FIG. 9 is an exploded view illustrating the heat sink with which the heat pipes are provided.

A heat sink 90 has a heat receiving plate 91 and a plurality of fins 92 a and 92 b which are disposed on the heat receiving plate 91 so as to be spaced apart from each other at a predetermined distance.

Two U-shaped heat pipes 93 and 94 are inserted into the plurality of the fins 92 a and 92 b from the front side toward the rear side of FIG. 7 so as to be tilted at a predetermined angle as illustrated in FIG. 8. In such an inserted state, the heat pipes 93 and 94 are disposed so as to be entirely covered with the plurality of the fins 92 a and 92 b.

The heat pipes 93 and 94 are provided, so that heat from the heat receiving plate 91 is also capable of being transferred to each of the fins 92 a and 92 b at a portion departing from the heat receiving plate 91, thereby improving the efficiency of heat release.

Each of the heat pipes 93 and 94 has a fine structure therein. Accordingly, for example, in cases where each of the heat pipes 93 and 94 has a diameter of φ 6 mm, a curvature radius of a curved portion of each of the heat pipes 93 and 94 is at most 15 mm.

As illustrated in FIGS. 7 and 9, in the heat sink 90, the fins 92 a which cover the curved portions of the heat pipes 93 and 94 individually have cutout portions 95 and 96 corresponding to the shapes of the curved portions. Accordingly, the heat pipes 93 and 94 are capable of being entirely disposed inside an assembly of the fins 92 a and 92 b. The fins are also provided so as to cover the curved portions, and such a configuration enables heat, which is transferred from the heat receiving plate 91 in this region, to be released.

For example, such techniques related to the existing art are disclosed in Japanese Laid-open Patent Publication Nos. 11-145354 and 2004-273632.

In the disclosed techniques, the cutout portions are not in contact with the curved portions of the heat pipes. Accordingly, in the fins having the cutout portions, areas in which the fins contact the heat pipes are reduced. Consequently, such fins have a problem in which the efficiency of the heat release is decreased relative to the fins not having cutout portions.

SUMMARY

According to an aspect of the invention, a heat sink includes a base, a first fin provided on the base and including a first cutout portion, a first heat pipe including a first linear portion and a first curved portion, the first curved portion being provided in the first cutout portion, and a second heat pipe including a second linear portion connected to the first fin with an adhesive having a heat conductivity.

The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a heat sink according to a first embodiment.

FIG. 2 illustrates the configuration of a heat sink.

FIG. 3 illustrates a positional relationship between heat pipes.

FIG. 4 illustrates a modification of the heat sink.

FIG. 5 illustrates another modification of the heat sink.

FIG. 6 illustrates a heat sink according to a second embodiment.

FIG. 7 illustrates a heat sink that is provided with heat pipes.

FIG. 8 illustrates a manner in which the heat pipes are provided.

FIG. 9 is an exploded view illustrating the heat sink with which the heat pipes are provided.

DESCRIPTION OF EMBODIMENTS

A heat sink according to the embodiments will be described with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a perspective view illustrating a heat sink according to a first embodiment.

A heat sink (radiator) 1 according to the embodiment has a base substrate (heat receiving plate) 2, fin unit 3, and heat pipes 4 a and 4 b.

The base substrate 2 has a rectangular shape.

Two grooves 21 and 22 are formed on the base substrate 2 in parallel with a side 2 a of the base substrate 2 so as to be spaced apart from each other at a predetermined distance. The heat pipe 4 a partially contacts the groove 21 through solder. The heat pipe 4 b partially contacts the groove 22 through solder.

The base substrate 2 contacts a heat source (not illustrated) through a thermally conductive member, such as grease, on the opposite side of the side on which the fin unit 3 is disposed.

Examples of the heat source include a semiconductor chip of a CPU or the like, a switching device, a resistance device, and a semiconductor package or the like having these components.

Examples of the material of the base substrate 2 include copper and aluminum.

A heat pipe (being different from the heat pipes 4 a and 4 b) that serves for heat diffusion may be embedded in the base substrate 2.

The fin unit 3 is disposed on the base substrate 2 through solder or the like.

The fin unit 3 includes a plurality of fins 3 a and 3 b. Each of the fins 3 a and 3 b has a plate shape. The plurality of the fins 3 a and 3 b are vertically arranged on the base substrate 2. Each of the fins 3 a and 3 b is regularly arranged from a side 2 b (front side) in a direction (to a rear side) indicated by an arrow that is parallel to the side 2 a. The fins 3 a are disposed on the front side and the rear side of the base substrate 2 respectively. The fins 3 b are disposed between the fins 3 a disposed on the front side and the fins 3 b disposed on the rear side.

Each of the fins 3 a and 3 b is provided so as to be spaced from other fins 3 a and 3 b at a predetermined distance.

Examples of the materials of the fins 3 a and 3 b include copper and aluminum.

For example, although not illustrated in FIG. 1, each of the fins 3 a and 3 b may be provided with a connecting portion that is used to connect one of the fins 3 a and 3 b to other fins 3 a and 3 b. Each of the fins 3 a and 3 b may be connected to other fins 3 a and 3 b through the connecting portion.

The heat pipes 4 a and 4 b are disposed inside the fin unit 3.

Each of the heat pipes 4 a and 4 b has a U-shaped body made of a metal such as copper or the like. The body is provided in the form of a tube. Ends of the U-shaped body are closed, and the inside thereof is airproofed. A wick having porous substances and fine grooves are provided on the inner wall of the body.

A small amount of a liquid (operating fluid) is enclosed in the body. Examples of the operating fluid include pure water, ammonia, and alternatives for chlorofluorocarbon or the like.

FIG. 2 illustrates the configuration of the heat sink.

Viewed from a front side to a rear side (in a front view), the heat pipe 4 a is disposed so as to be inclined to the left at a predetermined angle with respect to a direction vertical to the base substrate 2. In a front view, the heat pipe 4 b is disposed so as to be inclined to the right at a predetermined angle with respect to a direction vertical to the base substrate 2.

With reference to FIG. 2, the fin unit 3 is capable of being roughly divided into three assemblies including an assembly of the fins 3 a, an assembly of the fins 3 b and an assembly of the fins 3 a on the basis of forms thereof.

An assembly 51 that is illustrated on the left side of FIG. 2 is formed by assembling a plurality of the fins 3 a from the front side to the rear side in a predetermined number, the fins 3 a each having the same shape.

The assembly 51 is formed by collectively assembling the fins 3 a, and a curved portion 42 of the heat pipe 4 b is positioned inside the assembly 51 in such an assembled state.

Each of the fins 3 a of the assembly 51 has a circular hole (through-hole) 31, a concavity to form a semi-circular groove 32, and a cutout portion 33 corresponding to the curved portion 42 of the heat pipe 4 b. A linear portion 43 of the heat pipe 4 a is inserted into the hole 31 and passes thorough the same. A linear portion 45 of the heat pipe 4 a is inserted into the groove 32 and passes through the same.

An assembly 52 that is illustrated on the right side of FIG. 2 is formed by assembling a plurality of the fins 3 a from the most rear side to the front side in a predetermined number, the fins 3 a each having the same shape.

The assembly 52 is formed by assembling the fins 3 a, and a curved portion 41 of the heat pipe 4 a is positioned inside the assembly 52 in such an assembled state.

Each of the fins 3 a of the assembly 52 has the hole 31, a concavity to form the groove 32, and the cutout portion 33 corresponding to the curved portion 41 of the heat pipe 4 a. A linear portion 44 of the heat pipe 4 b is inserted into the hole 31 and passes thorough the same. A linear portion 46 of the heat pipe 4 b is inserted into the groove 32 and passes through the same.

The number of the fins 3 a which are provided with the cutout portions 33 is determined on the basis of the curvature radius of the curved portion 41. For example, in cases where the heat pipes 4 a and 4 b each have a diameter of φ 6 mm, curvature radiuses of the respective curved portions 41 and 42 are approximately 15 mm.

The cutout portions 33 are provided, so that the heat pipes 4 a and 4 b are entirely positioned inside the fin unit 3. Each of the cutout potions 33 has the same shape.

An assembly 53 is formed by assembling a plurality of the fins 3 b which are not used for the assemblies 51 and 52. The assembly 53 is formed by assembling the fins 3 b, and the linear portions 43 and 45 of the heat pipe 4 a and the linear portions 44 and 46 of the heat pipe 4 b are positioned inside the assembly 53 in such an assembled state.

Each of the fins 3 a of the assembly 51 has a hole 31 and a concavity to form a groove 32. Each of the fins 3 a of the assembly 52 has a hole 31 and a concavity to form a groove 32. The linear portion 43 of the heat pipe 4 a penetrates the holes 31 of the assembly 53 and the holes 31 of the assembly 51. The linear portion 44 of the heat pipe 4 b penetrates the holes 31 of the assembly 53 and the holes 31 of the assembly 52. The linear portion 45 of the heat pipe 4 a penetrates the grooves 32 of the assembly 53 and the grooves 32 of the assembly 51. The linear potion 46 of the heat pipe 4 b penetrates the grooves 32 of the assembly 53 and the grooves 32 of the assembly 52.

In the heat sink 1 having such a configuration, the linear portions 44 and 46 of the heat pipe 4 b contact the fins 3 a of the assembly 52. Furthermore, the ends of the linear portions 44 and 46 of the heat pipe 4 b contact the fin 3 a of the assembly 52 that is positioned closest to the rear. The ends of the heat pipe 4 b are provided so as to be visible from the outside.

Furthermore, the linear portions 43 and 45 of the heat pipe 4 a contact the fins 3 a of the assembly 51. Moreover, the ends of the linear portions 43 and 45 of the heat pipe 4 a contact the fin 3 a of the assembly 51 that is positioned closest to the front. The ends of the heat pipe 4 a are provided so as to be visible from the outside.

FIG. 3 illustrates a positional relationship between the heat pipes.

In FIG. 3, illustration of the components other than the heat pipes 4 a and 4 b is omitted.

FIG. 3 illustrates a positional relationship between the heat pipes 4 a and 4 b in a state in which the heat pipes 4 a and 4 b are inserted into the fin unit 3.

The heat pipes 4 a and 4 b are disposed by being inserted into the fin unit 3 from opposite ends in a manner in which the respective curved portions 41 and 42 intersect in a planar view. Namely, the heat pipe 4 a is disposed by being inserted from the rear side to the front side in FIG. 1 such that the linear portions of the heat pipe 4 a are inserted in a direction orthogonally intersecting the planar surfaces of the fins 3 a or 3 b (in a vertical direction). On the other hand, the heat pipe 4 b is disposed by being inserted from the front side to the rear side in FIG. 1 such that the linear portions of the heat pipe 4 a are inserted in a direction orthogonally intersecting the planar surfaces of the fins 3 a or 3 b (in a vertical direction).

The heat pipes 4 a and 4 b are disposed such that the respective curved portions 41 and 42 face each other.

A mechanism of the heat release in the heat sink 1 will be described.

In cases where the heat sink 1 is used, the heat sink 1 is placed such that the approximate center of the base substrate 2 contacts a heat source.

First, heat generated from the heat source is transferred to the base substrate 2.

Part of the heat that has been transferred to the base substrate 2 is transferred from the grooves 21 and 22 to the linear portions 45 and 46 of the heat pipes 4 a and 4 b, respectively. In addition, another part of the heat is directly transferred to the fins 3 a and 3 b.

In cases where the heat is transferred to the operating fluid of each of the heat pipes 4 a and 4 b, the temperature of the operating fluid is increased with the result that the operating fluid is evaporated. Steam generated by the evaporation moves through the curved portions 41 and 42 of the heat pipes 4 a and 4 b and moves to the linear portions 43 and 44, respectively.

The moved steam is cooled by the fins 3 a and 3 b to be liquidized. Specifically, the linear portion 43 of the heat pipe 4 a is disposed in the hole 31 provided on each of the fins 3 a of the assembly 51, and therefore the steam that has been moved to the linear portion 43 is cooled by transferring the heat from the hole 31 to each of the fins 3 a of the assembly 51, thereby being liquidized.

The linear portion 44 of the heat pipe 4 b is disposed in the hole 31 provided on each of the fins 3 a of the assembly 52, and therefore the steam that has been moved to the linear portion 44 is cooled by transferring the heat from the hole 31 to each of the fins 3 a of the assembly 52, thereby being liquidized.

The operating fluid which is reproduced by liquidizing the steam travels on the inner walls of the heat pipes 4 a and 4 b and returns to each of the linear portions 45 and 46 by capillary action.

A method of manufacturing the heat sink 1 will be described.

First, the substrate 2 on which the grooves 21 and 22 are formed is prepared.

The fins 3 a and 3 b are connected to each other using the above described connecting portions or the like, thereby producing the fin unit 3.

The fin unit 3 is placed on the base substrate 2 such that the groove 32 and the cutout portion 33 of the fin unit 3 are respectively aligned with the grooves 21 and 22 of the base substrate 2.

Cream-like solder is applied on the heat pipes 4 a and 4 b, and then the heat pipes 4 a and 4 b are inserted into the fin unit 3.

By virtue of this configuration, the linear portion 45 of the heat pipe 4 a is disposed along the groove 21. In addition, the linear portion 46 of the heat pipe 4 b is disposed along the groove 22.

Then, the resultant product is placed in a furnace to melt the cream-like solder. The solder is subsequently cured, thereby fixing the fin unit 3 and the heat pipes 4 a and 4 b to the base substrate 2.

With these processes, the heat sink 1 is capable of being manufactured.

As described above, the heat sink 1 has a configuration in which the linear portion 44 (43) of the heat pipe 4 b (4 a) contacts the fins 3 a of the assembly 52 corresponding to the curved portion 41 (42) of the heat pipe 4 a (4 b).

Specifically, in manufacturing, the linear portion 43 of the heat pipe 4 a is inserted in a direction opposite to a direction in which the linear portion 44 of the heat pipe 4 b is inserted.

Accordingly, the total area of the fins 3 a that contacts the heat pipes 4 a and 4 b is increased. Consequently, in the heat sink 1 having a configuration in which the heat pipes 4 a and 4 b are embedded in the fin unit 3, the efficiency of heat release is capable of being improved.

For example, in a configuration of a heat sink 90 illustrated in FIG. 7, heat pipes 93 and 94 are provided so as to be tilted at a predetermined angle. Therefore, a region that is positioned between cutout positions 95 and 96 of fin 92 a has a configuration in which such a region poorly receives heat from another region owing to the presence of the cutout portions 95 and 96. Accordingly, an inverted triangular portion that is positioned at the center of the fin 2 becomes a dead space that does not contribute to heat release.

However, in cases where the inclined angle of each of the heat pipes with respect to the base substrate is increased in order to decrease the area of the region that is disposed between the cutout portions, the heat is not transferred to the entire fin 92 a, resulting in decreased efficiency of heat release.

On the other hand, in the heat sink 1, the cutout portion 33 of each of the fins 3 a does not form the region to be interposed. Accordingly, the decrease in the efficiency of heat release is capable of being suppressed.

The heat pipes 4 a and 4 b are disposed so as to intersect each other, so that heat pipes each having a larger curvature radius are disposed, relative to the case in which the heat pipes are disposed so as not to intersect each other. Accordingly, the efficiency of heat release is further increased.

First Modification

FIG. 4 illustrates a modification of the heat sink. Description the same as that of the heat sink 1 will be omitted.

In the heat sink 1, the heat pipes 4 a and 4 b are disposed so as to be tilted at a predetermined angle with respect to a direction vertical to the base substrate 2.

However, in a heat sink is illustrated in FIG. 4, the heat pipes 4 a and 4 b are vertically disposed with respect to the base substrate 2.

For example, in cases where each of the heat pipes 4 a and 4 b has a diameter of φ 6 mm, curvature radiuses of the respective curved portions 41 and 42 are approximately 15 mm.

The heat sink is having such a configuration also provides an advantage in which the performance of the heat release is capable of being improved in each of the fins 3 a at a position at which the cutout position 33 is formed.

Second Modification

FIG. 5 illustrates a modification of the heat sink. Description the same as that of the heat sink 1 will be omitted.

In the embodiment described above, the heat pipes 4 a and 4 b are inserted from opposite ends and are disposed so as to intersect each other in planar view.

However, in a heat sink 1 b illustrated in FIG. 5, the heat pipes 4 a and 4 b are inserted from opposite ends and are disposed while so as to be tilted at a predetermined angle without intersecting each other.

For example, in cases where each of the heat pipes 4 a and 4 b has a diameter of φ 6 mm, curvature radiuses of the respective curved portions 41 and 42 are approximately 15 mm.

The heat sink 1 b having such a configuration also provides an advantage that the performance of the heat release is capable of being improved in each of the fins 3 a at a position at which the cutout position 33 is formed. Furthermore, the heat sink 1 b provides an advantage that the efficiency of the heat release in each of the fins 3 a is capable of being improved relative to the heat sink 1 a.

A heat sink according to a second embodiment will be hereinafter described.

Second Embodiment

The heat sink according to the second embodiment will be described on the basis of differences between the first embodiment and the second embodiment, and description the same as that of the first embodiment will be omitted.

FIG. 6 illustrates a heat sink is according to the second embodiment.

In the heat sink 1 c, three heat pipes 4 a, 4 b, and 4 c are disposed so as to be covered with the fins 3 a and 3 b.

Although the positional relationship between the heat pipes 4 a and 4 b is the same as that of the heat sink is of the first embodiment, the heat pipes 4 a and 4 b are disposed on the right side within the heat sink 1 a.

The heat pipe 4 c is disposed to the left of the heat pipes 4 a and 4 b so as to be tilted to the left at a predetermined angle with respect to a direction vertical to the base substrate 2.

The heat pipe 4 c has a shape the same as those of the heat pipes 4 a and 4 b.

The heat pipe 4 c is disposed by inserting ends thereof into the fin unit 3 from the front side in FIG. 6 to the rear side.

Each of the fins 3 a of the assembly 51 according to the embodiment has the hole 31, a concavity to form the groove 32, the cutout portion 33, and a cutout portion 34. The linear portion 43 of the heat pipe 4 a penetrates the hole 31. The linear portion 45 of the heat pipe 4 a penetrates the groove 32. The cutout portion 33 accommodates the curved portion 42 of the heat pipe 4 b. The cutout portion 34 accommodates the curved portion 47 of the heat pipe 4 c.

Each of the fins 3 a of the assembly 52 according to the embodiment has the hole 31, a concavity to form the groove 32, the cutout portion 33, and another hole (not illustrated). The linear portion 44 of the heat pipe 4 b penetrates the hole 31. The linear portion 46 of the heat pipe 4 b penetrates the groove 32. The cutout portion 33 accommodates the curved portion 41 of the heat pipe 4 a. The linear portion of the heat pipe 4 c penetrates another hole, described above.

Each of the fins 3 b of the assembly 53 has the two holes 31 and another hole (not illustrated). The respective linear portions 43 and 44 of the heat pipes 4 a and 4 b penetrates the two holes 31. The linear portion of the heat pipe 4 c penetrates another hole, described above.

In the heat sink 1 c, the linear portion 43 of the heat pipe 4 a is disposed in a region positioned between the heat pipes 4 b and 4 c in each of the fins 3 a.

Accordingly, heat is transferred from the linear portion 43 to an inverted triangular portion that is formed through being sectioned by the cutout portions 33 and 34 of each of the fins 3 a, so that a dead space is not generated, thereby being able to suppress the decrease in the efficiency of heat release.

The heat sink is of the second embodiment is capable of providing an advantage the same as that of the heat sink 1 of the first embodiment.

The heat sink is of the second embodiment is capable of further improving the efficiency of heat release.

Although a heat sink according to embodiments of the invention has been described on the basis of the above embodiments with reference to the accompanying drawings, embodiments of the invention are not limited to the above embodiments. The configuration of each component is capable of being appropriately replaced by another configuration having a function the same as that of each of the above embodiments. In addition, other objects and operations may be appropriately added to embodiments of the invention.

Furthermore, embodiments of the invention may be provided by appropriately combining two or more configurations (characteristics) of the above described embodiments.

All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. 

1. A heat sink comprising: a base; a first fin provided on the base and including a first cutout portion; a first heat pipe including a first linear portion and a first curved portion, the first curved portion being provided in the first cutout portion; and a second heat pipe including a second linear portion connected to the first fin with an adhesive having a heat conductivity.
 2. The heat sink according to claim 1, wherein the adhesive is made of a solder member.
 3. The heat sink according to claim 1, wherein the first curved portion is curved with respect to the first fin.
 4. The heat sink according to claim 1, further comprising: a second fin provided on the base and including a second cutout portion, wherein the second heat pipe further includes a second curved portion provided in the second cutout portion, and the first linear portion is connected to the second fin with an adhesive having a heat conductivity.
 5. The heat sink according to claim 4, wherein the second curved portion is curved with respect to the second fin.
 6. The heat sink according to claim 1, wherein the first fin includes a hole portion in which the second linear portion is inserted.
 7. The heat sink according to claim 4, wherein the first linear portion extends from the first curved portion toward the second fin, the second linear portion extends from the second curved portion toward the first fin, and the first curved portion faces the second curved portion.
 8. The heat sink according to claim 1, wherein the first cutout portion is inclined with respect to the base.
 9. The heat sink according to claim 4, wherein the second cutout portion is inclined with respect to the base.
 10. A heat sink comprising: a base; a plurality of fins provided on the base and including a first fin and a second fin, the first fin including a first cutout portion, the second fin including a second cutout portion; a first heat pipe including a first curved portion and a first linear portion extending from the first curved portion, the first curved portion being provided in the first cutout portion, the first linear portion being connected to the second fin, and a second heat pipe including a second curved portion and a second linear portion extending from the second curved portion, the second curved portion being provided in the second cutout portion, the second linear portion being connected to the first fin. 